In addition to Src family and SYK family kinases, B cells and T cells express a third family of receptor-proximal kinases called the Tec kinase family. The B cell-specific Tec family kinase is BTK; T cells express ITK as well as Tec and Rlk. Tec family kinases play an indispensable role in activation of phospholipase C and activation of calcium-dependent signaling cascades following antigen receptor triggering. BTK has been implicated in propagating signals downstream of LPS-TLR4 in B cells via signaling through the TLR4 co-receptor RP105/CD180. Mice congenitally lacking BTK or ITK show profound defects in B cell or T cell development and signaling, respectively. People with mutations or deletions in BTK suffer from X-linked agammaglobulinemia and X-linked immunodeficiency.

Specificity of this M4G3LN clone was determined by ELISA, flow cytometry, and western blotting.